Photoperiodic response in the soft tick, Ornithodoros turicata.

The effects of photoperiod on the feeding, development and quiescent behavior of the burrow-dwelling soft tick, Ornithodoros turicata (Dugès) were investigated. Ticks were assigned randomly to either continuous darkness (DD), a short-day photoperiod (L:D 10:14), a long-day photoperiod (L:D 14:10) or constant light (LL). Ticks reared under constant light succumbed to much higher mortality than those reared under the other conditions. However, photoperiod did not induce quiescent behavior in O. turicata; the ticks were active and fed regularly throughout the study. Also, ticks reared in continuous darkness developed more slowly than those reared under short-day or long-day conditions. In contrast, pre-oviposition period was significantly longer for ticks reared in long-day conditions. Egg-hatch success was significantly higher for ticks reared in continuous darkness than for those reared under the photoperiods. The stage-specific effects of photoperiod on O. turicata are adaptive; these ticks very likely utilize photoperiod information to predict seasonal conditions.